Personally I have only one bad Honda engine but the mower it was so badly abused that a 21" bar only measure 12" and the engine never had an oil change therefore probably the reason the flywheel side bushing was worn completely out yet it still ran.
Just because they are now using fixed speed system on some designs doesn't cheapen the engine, just removes the throttle cable expense. Now Chondas are a different story here as they can be terrible.
As for dating I have been told you need to contact Honda for that as it is an internal coding setup, mostly a serial number range system.
